1. Field of the Invention
The invention relates to stage devices and exposure apparatus and methods. In particular, the invention relates to stage devices that may be used in an exposure apparatus in which an energy beam having a wavelength of 200 nm or less is used for exposure, and to an exposure-apparatus and method using the stage device.
2. Description of Related Art
Hitherto, various types of exposure apparatus have been used in lithographic processes in the manufacture of semiconductor devices, liquid crystal display devices, and the like. Recently, reduction-projection exposure apparatus of a step-and-repeat type (steppers) and scanning projection exposure apparatus of a step-and-scan type (scanning stepper) are relatively widely used.
In these types of exposure apparatus, patterns of reticles (masks) are transferred onto a plurality of shot regions on a wafer (substrate). To that end, a wafer stage is driven in two-dimensions, in directions X and Y, by a driving mechanism including, for example, a linear motor. A reaction force generated by driving the wafer stage has been discharged by being mechanically transmitted to a floor (ground) by using a frame member disposed on a base (for example, a floor or a base plate as the foundation of the apparatus) vibrationally (dynamically) isolated from the stage, as described in, for example, U.S. Pat. No. 5,528,118.
In the case of the scanning stepper, a reticle stage in addition to the wafer stage must be driven in a given scanning direction. In order to deal with the reaction force generated by driving the reticle stage, a counter-mass structure that relies upon the law of conservation of momentum is generally used along a scanning direction (refer to, for example, U.S. patent application Ser. No. 09/260,544). The counter-mass structure moves in a direction opposite to the direction in which the stage moves in order to discharge (absorb) the reaction force. Movement of the counter-mass also maintains the center of gravity in the movement direction constant to avoid swaying of the apparatus. Another method for discharging a reaction force generated by moving a reticle stage is a method in which the reaction force is mechanically discharged to a base, such as a floor (ground), by using a frame member (see, for example, U.S. patent application Ser. No. 08/416,558).
In the known projection-exposure apparatus, a reaction force resulting from driving a stage is discharged to a base. Vibrations caused in the base by the reaction force have been damped by a vibration isolator, such as an anti-vibration table (vibration-elimination table) on which the projection optical system and stage are mounted, thereby suppressing vibration of the projection optical system and the stage caused by the reaction force.
Recently, vibration isolation has been improved by disposing multiple vibration-isolation tables in an exposure apparatus in situations where the effect of a reaction force, due to driving a stage, on the accuracy of exposure, although small, is non-negligible, even when the reaction force is discharged to a frame disposed directly on a base.
Semiconductor devices and the like have been more highly integrated over the years, thereby making circuit patterns smaller. Thus, projection-exposure apparatus have been required to have higher resolution. In order to improve resolution, it is known to increase the numerical aperture of the projection optical system (NA-increase) and to shorten the wavelength of the exposure beam. A most effective method for improving resolution is to shorten the wavelength of the exposure beam because the NA-increase decreases the depth of focus. Therefore, the wavelength of exposure beams has been decreasing over the years, and an exposure apparatus having, as a light source, an ArF-excimer laser having an output wavelength of 193 nm is at the stage of practical application. Moreover, exposure apparatus having light sources with even shorter wavelengths, such as an F2-laser (output wavelength of 157 nm) and an Ar2-laser (output wavelength of 126 nm), are being considered.
It is believed that the device rule (practical minimum line width) will be 0.1 xcexcm or less in the future. There is almost no doubt that an electron beam exposure apparatus (hereinafter referred to as xe2x80x9cEB-exposure apparatusxe2x80x9d) will be one of the dominant alternatives as an exposure apparatus for realizing exposure of such microscopic patterns.
Vacuum ultraviolet radiation beams from, for example, the F2-laser, are difficult to transmit through air. Therefore, the overall light path thereof must be enclosed in a chamber or the like, and the air in the chamber must be replaced by inert gas such as nitrogen or helium, so as to remove the air from the section through which the light path is to be formed. That is, in an exposure apparatus using a vacuum ultraviolet light source, the reticle stage and the wafer stage are enclosed in respective chambers.
Similarly, in an EB-exposure apparatus, the wafer stage and the like are enclosed in evacuated chambers.
In an exposure apparatus using a near-ultraviolet light source such as an ArF-excimer laser, at least one part of the light path is preferably enclosed in a chamber or the like. The chamber or the like is preferably purged by replacing the air therein with clean air from which organic substances and the like have been removed, or with an inert gas such as nitrogen or helium.
However, in these exposure apparatus provided with chambers for enclosing the light paths, it is difficult to use the technology as it is, which is disclosed in, for example, U.S. Pat. No. 5,528,118 described above, to discharge the reaction force caused by driving, for example, wafer stages.
Accordingly, it is a first object of the invention to provide a stage device in which a reaction force generated by driving a stage can be discharged to the outside while maintaining the stage in a predetermined gas atmosphere condition.
It is a second object of the invention to provide an exposure apparatus in which the accuracy of exposure can be improved.
According to a first aspect of the invention, a stage device includes a stage, an airtight chamber, a driver and a reaction-force-discharging structure. The stage supports an object such as, e.g., a mask or a substrate. The airtight chamber receives the stage in a hermetic state. The driver is disposed in the airtight chamber and includes a movable member connected to the stage and a stationary member that cooperates with the movable member to generate a driving force to drive the stage. The reaction-force-discharging structure discharges a reaction force that is applied to the stationary member when driving the stage to the outside of the airtight chamber via a transmitting member, at least part of the transmitting member being connected to the airtight chamber.
In the present specification, the phrase xe2x80x9ccooperatesxe2x80x9d as used, for example, in xe2x80x9ca stationary member that cooperates with the movable member to generate a driving forcexe2x80x9d means that a driving force is generated by an interaction such as an electromagnetic (or magnetic) interaction between the stationary member and the movable member.
In the stage device according to this aspect of the invention, when the stage is driven by the driver disposed in the airtight chamber, a reaction force is generated by that driving and is applied to the stationary member. The reaction force is discharged to the outside of the airtight chamber by the reaction-force-discharging structure via the transmitting member, at least a portion of which is connected to the airtight chamber. When the airtight chamber receiving the stage is set to a predetermined gas atmosphere (including air from which organic substances and the like have been removed), the reaction force caused by driving the stage can be discharged to the outside while maintaining the predetermined atmosphere.
In this case, the airtight chamber may receive the stage and the driver, and the airtight chamber may be formed by a chamber partition, part of which is provided with an aperture. One end of a hollow resilient sealing member can be connected to a periphery of the aperture of the chamber partition. The other end of the sealing member can be provided with a closing member for closing an opening on that other end. The reaction-force-discharging structure may include a connecting structure, at least one part of which is inserted into an inner space of the sealing member. The connecting structure includes a vibration-damper connected to the closing member, and that connects the stationary member and the transmitting member to each other.
The closing member may be disposed outside the chamber or it may be disposed inside the chamber. In the former case, the vibration-damper may connect the stationary member and the closing member disposed outside the chamber, and the closing member may be connected to the transmitting member. In the latter case, the connecting structure may further include a mounting member to be mounted on the transmitting member. The closing member may be disposed in the chamber, one side thereof being connected to the stationary member. The vibration-damper may connect the other side of the closing member and the mounting member. In the latter case, since the connecting member is disposed inside the chamber, the internal cubic dimensions and the distance between the chamber and the transmitting member can be reduced compared with the former case, whereby the footprint of the device can be reduced.
In the stage device according to the first aspect of the invention, when the reaction-force-discharging structure includes the vibration-damper and the connecting structure for connecting the stationary member and the transmitting member, the vibration-damper may be pivotal along a plane perpendicular to the axis thereof and along two axes perpendicular to each other. When a force caused by a reaction force is applied along the plane perpendicular to the axis of the vibration-damper, the force is absorbed by pivoting motion of the vibration-damper. When the force is applied along the axis of the vibration-damper, the force is efficiently damped by the damping function of the vibration-damper.
Although in the stage device according to the first aspect of the invention, the vibration-damper may be configured in any manner as long as the reaction force by driving the stage can be damped, the vibration-damper is preferably a shock absorber having the functions of a damper and a resilient member.
When the airtight chamber is formed by the chamber partition, the hollow sealing member, and the closing member, the stage device according to the first aspect of the invention may further include an external frame dynamically isolated from the chamber partition and mounted with the transmitting member. The reaction force caused by driving the stage and that is applied to the stationary member is transmitted to the external frame via the transmitting member, at least part of which is connected to the airtight chamber. Since the external frame is dynamically isolated from the chamber, vibration caused by the reaction force transmitted to the external frame is substantially suppressed to zero.
The transmitting member may be mounted on the external frame via a threaded part so as to be movable toward and away from the connecting structure, and the transmitting member and a particular member, which is disposed opposite to the stationary member, among the components of the connecting structure, may be fixed to each other via a fixing structure. The chamber partition mounted with the connecting structure is disposed at a predetermined position, is moved by the threaded part to another position in which the transmitting member comes into contact with the particular member constituting the connecting structure, and the particular member and the transmitting member are fixed to each other by the fixing structure, whereby the assembly is easily completed. As described above, the chamber partition and the connecting structure may be assembled in advance as a unit.
The fixing structure may be a bolt having a thread to mate with a threaded hole formed in at least one of the particular member and the transmitting member, for fastening the particular member and the transmitting member to each other. The fixing structure may be a structure for holding the particular member by a movement of the transmitting member toward the connecting member.
The stage device according to the first aspect of the invention may further include a conveying system for loading and unloading the material to and from the airtight chamber. In this case, loading of the material to the stage in the airtight chamber and unloading of the material from the stage can be performed.
According to a second aspect of the invention, a stage device includes a plurality of stages, each stage supporting an object; an airtight chamber that receives the plurality of stages in a hermetic state; a driver disposed in the airtight chamber and including a movable member connected to each of the plurality of stages and a stationary member associated with each movable member to generate a driving force to drive each of the plurality of stages in cooperation with the movable member; and a reaction-force-discharging structure to discharge a reaction force applied to the corresponding stationary member by driving of at least one of the plurality of stages to the outside of the airtight chamber via a transmitting member, at least a part of which is connected to the airtight chamber.
When one of the stages is driven by the driver disposed in the airtight chamber, a reaction force generated by driving of the stage is applied to the stationary member. The reaction force is discharged to the outside of the airtight chamber by the reaction-force-discharging structure via the transmitting member. When the airtight chamber receiving the plurality of stages is set to a predetermined gas atmosphere (including air from which organic substances and the like have been removed), the reaction force can be discharged to the outside while maintaining the predetermined atmosphere.
According to a third aspect of the invention, an exposure apparatus for exposing a substrate to energy beams, thereby forming a predetermined pattern on the substrate, includes a substrate stage to support the substrate. It also includes an airtight chamber that receives the substrate in a hermetic state. In addition, a driver is disposed in the airtight chamber and includes a movable member connected to the substrate stage and a stationary member that generates a driving force to drive the substrate stage in cooperation with the movable member. It also includes a reaction-force-discharging structure that discharges a reaction force that is applied to the stationary member when the driver drives the substrate stage to the outside of the airtight chamber via a transmitting member, at least a part of which is connected to the airtight chamber.
When the substrate stage is driven by the driver disposed in the airtight chamber, a reaction force is generated by driving the substrate stage and is applied to the stationary member. The reaction force can be discharged to the outside of the airtight chamber by the reaction-force-discharging structure via the transmitting member. When the airtight chamber is set to a predetermined gas atmosphere (including air from which organic substances and the like have been removed), the reaction force caused by driving the substrate stage can be discharged to the outside while maintaining the predetermined atmosphere. For example, by setting the airtight chamber to an atmosphere of an inert gas such as nitrogen and by exposing a substrate to vacuum ultraviolet radiation beams, accurate exposure is possible. In this case, since the reaction force caused by driving the substrate stage does not significantly affect the control of position of the stage, accurate control of the position of the stage is possible, whereby the exposure operation is improved such that variations in position of the transferred patterns do not occur.
Alternatively, for example, the airtight chamber may be evacuated, and electron beams as energy beams may be used for the exposure of the substrate, whereby an improved exposure is also made possible.
The exposure apparatus according to the invention may further include a laser interferometer that determines the position of the substrate stage by measuring the length of beams of which at least one part of the light path is disposed in the airtight chamber. In this case, when the airtight chamber is set to an atmosphere of an inert gas such as nitrogen (or is evacuated), the shimmering by air which causes variations in the measurement by the laser interferometer can be avoided, because the atmosphere in the airtight chamber can be maintained. Thus, an accurate determination of the position of the wafer stage is made possible.
The exposure apparatus according to the invention may further include a projection optical system for applying the energy beams to the substrate. In this case, for example, the airtight chamber is set to an atmosphere of an inert gas such as nitrogen, and the exposure of the substrate is performed by using vacuum ultraviolet radiation beams, whereby exposure with high resolution is possible.
The exposure apparatus according to the invention may further include a chamber in addition to the airtight chamber for receiving the projection optical system.
According to a fourth aspect of the invention, an exposure apparatus for applying energy beams to a mask, thereby transferring a pattern of the mask to the substrate, includes a mask stage for supporting the mask. It also includes a mask chamber that receives the mask stage in a hermetic state. In addition, a mask-driver is disposed in the mask chamber and includes a movable member connected to the mask stage and a stationary member that generates a driving force to drive the mask stage in cooperation with the movable member. The device also includes a reaction-force-discharging structure that discharges a reaction force applied to the stationary member when the driver drives the mask stage to the outside of the mask chamber via a transmitting member, at least a part of which is connected to the mask chamber.
When the mask stage is driven by the driver disposed in the airtight chamber, a reaction force generated by driving the mask stage is applied to the stationary member. The reaction force is discharged to the outside of the airtight chamber by the reaction-force-discharging structure via the transmitting member connected to the airtight chamber. When the airtight chamber receiving the mask stage is set to a predetermined gas atmosphere (including air from which organic substances and the like have been removed), the reaction force caused by driving the mask stage can be discharged to the outside while maintaining the predetermined atmosphere. Therefore, accurate exposure is made possible by setting the airtight chamber to an atmosphere of an inert gas such as nitrogen, and by transferring the pattern of the mask to the substrate by using vacuum ultraviolet radiation beams.
According to a fifth aspect of the invention, a method for manufacturing an exposure apparatus for exposing a substrate to energy beams, thereby forming a predetermined pattern on a substrate, includes the steps of providing a substrate stage for supporting the substrate; closing an airtight chamber in a hermetic state, the airtight chamber receiving a driver, together with the substrate stage, including a movable member connected to the substrate stage and a stationary member for generating a driving force for driving the substrate stage in cooperation with the movable member; and providing a reaction-force-discharging structure for discharging a reaction force applied to the stationary member when the driver drives the substrate stage to the outside of the airtight chamber via a transmitting member, at least a part of which is connected to the airtight chamber.
The substrate stage for supporting a substrate is provided, and the driver is received in the airtight chamber in a hermetic state together with the substrate stage. The driver includes the movable member connected to the substrate stage and the stationary member for generating a driving force to drive the substrate stage in cooperation with the movable member. The reaction-force-discharging structure is provided, for discharging the reaction force generated by driving the substrate stage to the outside of the airtight chamber via the transmitting member. Then, the driver, the substrate stage, the reaction-force-discharging structure, and various other components, such as an illumination optical system, are mechanically, optically, and electrically assembled and adjusted, whereby the exposure apparatus according to an aspect of the invention is manufactured.